6.41 Tuesday, March 24, 2015

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Top new questions this week: 
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[Faster position list construction from a "take instructions" list] http://mathematica.stackexchange.com/questions/77542/faster-position-list-construction-from-a-take-instructions-list

Take some list, e.g., 1,2,3,4,5, and a "take instructions" list, say 1,1,2,1,1.

The latter is read as "take the first element from the list, drop it from the list, take the first element of the ...

- asked by rasher (16 votes), answered by 2012rcampion (9 votes)

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[Capturing Data from an Android Phone] http://mathematica.stackexchange.com/questions/77514/capturing-data-from-an-android-phone

Is there a way to capture Data from an android phone to be later analyzed in Mathematica?

- asked by Zviovich (10 votes), answered by Zviovich (10 votes)

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[Match opening and closing parentheses?] http://mathematica.stackexchange.com/questions/77779/match-opening-and-closing-parentheses

Suppose I have a List of the form:

lst="(", "(", "(", ")", "(", ")", ")", ")"

By running Position[lst, "("] and Position[lst, ")"], I can get the positions of the opening and closing parentheses ...

- asked by becko (8 votes), answered by Simon Woods (12 votes)

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[Segmenting Sections of Lines in an Image] http://mathematica.stackexchange.com/questions/77972/segmenting-sections-of-lines-in-an-image

I have taken several gps readings while driving around town.

gpsPositions=GeoPosition[33.657, -84.5197, 33.6687, -84.4977, 33.692, -84.4907, 33.7057, -84.4287, 33.7431, -84.4027, ...

- asked by Zviovich (7 votes), answered by nikie (8 votes)

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[Flatten nested lists]http://mathematica.stackexchange.com/questions/78030/flatten-nested-lists

I have a list as follows

lis= a, b, c,d,e, f, g,h,i

which I would like to flatten to

flattenLis=a,b,c,d,e,f,g,h,i

Does anyone have a hint. All my flatten attempts did not ...

- asked by Phadreus (7 votes), answered by Kuba (7 votes)

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[How to make a binary function associative? (Or define an n-ary function?)]http://mathematica.stackexchange.com/questions/77913/how-to-make-a-binary-function-associative-or-define-an-n-ary-function

Suppose I have a simple function that I assign to an operator

f[a_, b_] := a + b 
CirclePlus = f

Then I want to write

1 (+) 2 (+) 3

But it doesn’t work, because it’s trying to evaluate f[1,2,3].

...

- asked by Noon Silk (7 votes), answered by halirutan (9 votes)

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[Strange answer from StringReplace] http://mathematica.stackexchange.com/questions/77771/strange-answer-from-stringreplace

I have a list of strings and I would check if there is an empty string element, that’s "", because I need to replace it with a "0". I try the following

StringReplace[{"90", "", "20"}, "" -> "0"]

...

- asked by bobknight (7 votes), answered by Sjoerd C. de Vries (8 votes)

================================== Greatest hits from previous weeks: ==================================

[How to use Mathematica functions in Python programs?] http://mathematica.stackexchange.com/questions/4643/how-to-use-mathematica-functions-in-python-programs

I’d like to know how can I call Mathematica functions from Python.

I appreciate a example, for example, using the Mathematica function Prime.

I had search about MathLink but how to use it in Python ...

- asked by GarouDan (28 votes), answered by GarouDan (10 votes)

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[A one line proof that one is zero using Mathematica 10] http://mathematica.stackexchange.com/questions/65624/a-one-line-proof-that-one-is-zero-using-mathematica-10

a = (Sqrt[2] + 1) (Sqrt[2] - 1) - 1; a/a, Simplify[a]/a, b/b == Simplify[b]/b

1, 0, True

This one line "proof" that one equals zero is disturbing (and could possibly lead to wrong results ...

- asked by Gregoire Nicollier (11 votes), answered by Szabolcs (24 votes)

================================== Can you answer these? ==================================

[How to simplify an expression with a radical sign nesting in a radical sign] http://mathematica.stackexchange.com/questions/77902/how-to-simplify-an-expression-with-a-radical-sign-nesting-in-a-radical-sign

Is there a function can simplify an expression with a radical sign nesting in a radical sign in Mathematica? I use V9.

RatDenmon is a function that can rationalize the denominator.

- asked by user27189 (1 vote)

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[Plotting data with four variables; two labels for one of the axes] http://mathematica.stackexchange.com/questions/77727/plotting-data-with-four-variables-two-labels-for-one-of-the-axes

I am having difficulty related to 3D plotting task. I have a set of data points in the following form :

data=1x, 1y1,1y2,1z, 2x,2y1,2y2,2z,....nx,ny1,ny2,nz

The set of points ...

- asked by user91411 (2 votes)

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[Lisp Interpreter] http://mathematica.stackexchange.com/questions/77661/lisp-interpreter

What is the cleanest way to build a lisp interpreter inside Mathematica.

I’m not looking for all the functions to be implemented but instead just the basic syntax.

- asked by William (3 votes)